Weapon and Armor Proficiency: Shadowcasters are proficient with simple weapons and with light armor. They are not proficient with medium armor, heavy armor, or shields of any type. A shadowcaster can cast shadowcaster mysteries gained from the shadowcaster class (but not other arcane spells gained from other spellcasting classes) in light armor without suffering any arcane spell failure chance, but suffers the normal chance of failure for casting in medium armor, heavy armor, or when using any type of shield.

Fundamentals of Shadow (Su): A shadowcaster masters certain basic powers before proceeding to deeper secrets of shadow. These powers—known as fundamentals of shadow (see below for a list of the different fundamentals)—are cast like any other spell, but they not consume any slots and may be used again. The save DC for a fundamental—if any—is equal to 10 + the shadowcaster’s Intelligence modifier.

Shadowcasting: A shadowcaster casts arcane spells drawn from the shadowcaster spell list; these are known as mysteries. To cast a spell, a shadowcaster must have an Intelligence score equal to at least 10 + the spell level. The Difficulty Class for a saving throw against a shadowcaster’s spell is 10 + the spell level + the shadowcaster’s Intelligence modifier.

Like other spellcasters, a shadowcaster can cast only a certain number of mysteries of each spell level per day. Her base daily spell allotment is shown on the chart below. In addition, she receives bonus mysteries per day if she has a high Intelligence score.

Mysteries represent thought patterns and formulae so alien that other spells seem to pale in comparison. Mysteries have somatic components, armor-based spell failure chance (but see weapon and armor proficiencies, above), and are subject to interruption (but they do not require material component, foci, or verbal components; all mysteries have somatic components, however). Whenever a shadowcaster casts a mystery, observers can make a DC 15 Spot check to note that her shadow is making different gestures from the ones she makes when casting the mystery.

In order to invoke a mystery, a shadowcaster must have an Intelligence score of at least 10 + the level of the mystery. The save DC for a mystery cast by a shadowcaster is 11 + the level of the mystery + the shadowcaster’s Intelligence modifier.

A shadowcaster’s caster level is equal to her shadowcaster level.

A shadowcaster has access to all mysteries of any level that she is able to cast.

Bonus Feats: At 1st level, a shadowcaster gains a bonus feat from the following list: Line of Shadow, Nocturnal Caster, Shadow Reflection, Shadow Cast, Shadow Familiar, or any Metamagic or Item Creation feat. She must meet all prerequisites listed in order to choose the feat. At 5th level, and every four levels gained as a shadowcaster thereafter, she may choose one additional bonus feat from this list.

Deep Shadows (Ex): At 2nd level, a shadowcaster’s power beckons to the shadows around her, causing them to warp and extend to cover her with their darkness. She gains a +2 competence bonus on all Stealth skill checks at any time she is not in direct sunlight or the radius of a daylight spell. At 8th level, and every six shadowcaster levels gained thereafter, this bonus increases by +2 to a maximum bonus of +8 at 20th level.

Umbral Sight (Su): Starting at 3rd level, a shadowcaster’s vision extends slightly into the Plane of Shadow. She retains the ability to see perfectly out to a distance of 30 feet (including color vision), regardless of the normal level of illumination or the presence of magical darkness. At both 11th and 19th level, the range of her umbral sight increases by an additional 30 feet.

Shadowy Illumination (Ex): At 4th level, the connection between a shadowcaster and the powers of shadow begins to manifest around her person. Non-magical sources of illumination (other than direct sunlight) within 10 feet of the shadowcaster are weakened in her presence, reducing the level of illumination by one step (i.e. bright light becomes normal light, normal light becomes dim light, etc.) to the stage of dim light. Dim light cannot be reduced any further (to darkness). In addition to being reduced in illumination, the radius in which these light sources illuminate is also reduced by 5 feet. (For example, a torch that provides normal illumination in a 20-foot radius within 10 feet of a shadowcaster sheds dim light in a 15-foot radius instead).

This ability is not under the conscious control of the shadowcaster and is always in effect. At 7th level, and every three levels gained thereafter as a shadowcaster, the radius of her shadowy illumination increases by an additional 10 feet (to a maximum of 60 feet at 19th level). Starting at 10th level, non-magical sources of illumination within a shadowcaster's effective range have the area which they illuminate reduced by 10 feet rather than 5 feet and magical sources of illumination have their radius reduced by 5 feet. At 18th level, the power of this ability increases yet again, reducing the radius of illumination for non-magical sources of light by 15 feet and magical sources of light by 10 feet.

Sustaining Shadow (Ex): Upon reaching 5th level, a shadowcaster’s bond to the Plane of Shadow allows her to absorb the dark energies found there, mitigating certain biological needs. She need eat only a single meal each week to maintain her health. At 10th level, she needs to sleep only 2 hours each night (although she can still only regain her spent mysteries once every twenty-four hours). At 15th level, she becomes immune to both poison and disease. Finally, at 20th level, she no longer needs to breathe, eat, drink, or sleep (but must still have 2 hours of rest to refresh her expended mysteries).

Shadows of Cold (Ex): Beginning at 6th level, a shadowcaster becomes accustomed to the soul-numbing cold of the Plane of Shadow. She gains cold resistance 10. This cold resistance increases by 10 at both 10th and 14th level. At 18th level, she becomes immune to all cold damage.

Shadow Meld (Su): Starting at 12th level, a shadowcaster can meld with existing shadows. When in an area of dim light, the shadowcaster can, as a standard action, meld with existing shadows. While melded, the shadowcaster becomes invisible (as per the spell), incorporeal (as per the monster special quality), and emits no scent (and thus cannot be pinpointed by creatures with the scent special quality). Nor will the use of blindsense, blindsight, or tremorsense detect the shadowcaster while she is in this state.

While shadow melded, a shadowcaster retains full awareness of her surroundings, including vision, hearing, and her sense of smell.

Attempts to magically discern a shadowcaster’s location while she is melded with the shadows are extremely difficult; even if the searcher is using spells such as see invisibility or true sight. The searcher must succeed on an opposed caster level check to spot the shadowcaster while she is in this state.

If the square in which a shadowcaster is melded is illuminated by bright light, the meld immediately ends and she cannot use this ability again until one hour has passed.

There is no duration limit on how long a shadowcaster can remain melded to shadow; however, while she is melded, she may take NO actions (not even free actions). This includes speaking, moving (including 5’-steps), activating a magic item, or casting a spell. If the shadowcaster takes any action, she is no longer melded with shadow and cannot use this ability again until one hour has passed.

Master of Shadows (Ex): At 20th level, as a standard action, a shadowcaster may transform herself and her equipment into an incorporeal being of shadow. She may remain in shadowform for up to one minute for every shadowcaster level she has gained. This duration need not be used consecutively, but each use counts as one minute duration, regardless of the actual time spent in shadowform.

While in shadowform, the shadowcaster gains a fly speed of 60 feet with perfect maneuverability. She gains a deflection bonus to her Armor Class equal to her Intelligence modifier. She may freely cast spells at corporeal creatures with no miss chance due to her own shadowform.